I think you have a false foundation here. I think you are assuming that people value safety from extremists more than the intellectual certainty of certainty and I doubt very much that they do. In the end, this is a big scary universe and people need that sense of certainty, that sense of belonging.

By encouraging doubt, the result is that while people might well throw aside a certainty that might lead them to embrace one form of extremism, they do so only to embrace another certainty, which leads to an entirely different fanaticism.

I don't t know though. Perhaps doubt, is an answer, but only if it's not taken to extremes.